著者
KUBOTA,SHIN
出版者
Zoological Society of Japan
雑誌
Zoological science
巻号頁・発行日
vol.9, no.2, 1992-04-15

A new hydromedusa Eirene lacteoides (Leptomedusae; Eirenidae) from Toba, Mie Prefecture, Japan is described based on the laboratory-reared 18 male medusae and 33 immature ones. The new species resembles Eirene lactea (Mayer, 1900) in having distal projections of peduncle, but can be distinguished by the presence of an adaxial papilla on every well-developed tentacular bulb and even on some small tentacular bulbs bearing very short tentacles. The development of medusa, the nematocyst equipment, and the distributional records of E. lacteoides are also described.
著者
Yamagishi Ayaka Yao Izumi Johnson Kevin P. Yoshizawa Kazunori
出版者
Zoological Society of Japan
雑誌
Zoological Science (ISSN:02890003)
巻号頁・発行日
vol.31, no.6, pp.383-389, 2014-06
被引用文献数
2 2

Data from gene sequences and morphological structures were collected for the gull feather lice, Saemundssonia lari, Quadraceps punctatus, and Q. ornatus, parasitizing Larus crassirostris and L. schistisagus. Saemundssonia lari was collected from both gull species, and no detectable morphological and genetic differences were found between lice collected from the two different hosts. In contrast, Q. punctatus was only collected from L. crassirostris, whereas Q. ornatus was only collected from L. schistisagus. The two Quadraceps species were genetically highly divergent, and body-size differences corresponding to the gull's body size (Harrison's rule) were also detected between them. Both Quadraceps species were collected from the interbarb of the remex or rectrix, and a match in body size between the louse and the interbarb space may be important in escape from host preening defenses. In contrast, Saemundssonia is a head louse, inhabiting the finer feathers of the head and neck, which the bird cannot preen. A close match to host body size may be less important for lice in the head microhabitat. The differences in the pattern of host-specificity between Saemundssonia and Quadraceps on the two focal host species of this study were probably due to their different microhabitat preferences. More broadly, comparisons of the gene sequences of S. lari and Q. punctatus to those from other gull hosts showed that genetically almost undifferentiated populations of both species were distributed on wide range of gull species. Frequent interspecific hybridization of gulls is one possible factor that may allow these lice to maintain gene flow across multiple host species.
著者
Endo Hideki Niizawa Nobuharu Komiya Teruyuki Kawada Shinichiro Kimura Junpei Itou Takuya Koie Hiroshi Sakai Takeo
出版者
Zoological Society of Japan
雑誌
Zoological Science (ISSN:02890003)
巻号頁・発行日
vol.24, no.10, pp.1005-1011, 2007-10
被引用文献数
13

The gross anatomy of the mastication system of the giant anteater (Myrmecophaga tridactyla) was examined by means of three-dimensional image analysis. The anteater rotates the mandibles medially and laterally to control its tongue when it is elongated and to house it when it is relaxed. Three-dimensional CT image analysis demonstrated that the shape and size of the oral cavity changes drastically when the mandibles are rotated. The oral cavity expands bilaterally when the dorsal part of the mandibles bend medially. Macroscopic observations and muscle-weight data supported the observation that the superficial temporal and medial pterygoid muscles act as the main medial and lateral rotators of the mandible, respectively. The low height of the mandibular ramus and the incomplete zygomatic arch in this species represent adaptations for the rotational movement of the mandibles, since they both contribute to the medially oriented transmission of force from the temporal muscles and to preventing collision between the mandibles and the cranium during the rotational movement.
著者
Nishi Hirotaka Sota Teiji
出版者
Zoological Society of Japan
雑誌
Zoological Science (ISSN:02890003)
巻号頁・発行日
vol.24, no.5, pp.475-485, 2007-05
被引用文献数
7

We studied genetic variation within the Japanese land snail Euhadra herklotsi, which occurs on Kyushu and the surrounding islands, using partial sequences of the mitochondrial COI gene and nuclear ITS2 genes. The phylogenetic analysis revealed the existence of two major clades: clade N in the north and clade S in the south. These clades were parapatric and overlapped in southern Kyushu. Genetic divergence was high in clade N, whereas it was much lower in clade S. In addition, isolation-by-distance within each clade was implied. Since no current geographical barriers separate these clades, the genetic structure of clade S might have been influenced by historical events, such as volcanic activity, and a resulting population bottleneck followed by range expansion. The genital characteristics of clade-S snails were distinct from those of clade-N snails, and snails in both clades were sympatric at one locality. The shells of clade-N snails were generally larger than those of clade-S snails, but the shell-size variation within each clade could not be explained simply by environmental variables. Our study suggests that E. herklotsi likely consists of two sibling species. The taxonomic status of the previously proposed subspecies of E. herklotsi and related species requires reassessment.
著者
Kurihara Takeo Shikatani Mayu Nakayama Kouji Nishida Mutsumi
出版者
Zoological Society of Japan
雑誌
Zoological Science (ISSN:02890003)
巻号頁・発行日
vol.23, no.11, pp.999-1008, 2006-11
被引用文献数
7

In many benthic organisms with a planktonic larval stage, local populations have different morphology. Such difference may arise from some of the following proximate mechanisms. “Local recruitment (LR)”: no larvae move between local populations, and segregated populations possess alleles coding for locally adaptive morphology. “Intragenerational selection (IS)”: larvae move between local populations, and individuals with alleles for locally adaptive morphology survive after recruitment. “Phenotypic plasticity (PP)”: larvae move between local populations and show phenotypic plasticity to adapt to a locality after recruitment. We examined which mechanism explains our finding that a planktonic developer Turbo coronatus coronatus (Gastropoda) had significantly longer spines on its shell on more exposed shores at scales of < 2 km. Experiments at Ishigaki Island, Okinawa, Japan, showed the following results. (a) Shorter- and longer-spined populations occurring within 2 km showed non-significant ϕ low st values (−0.0040 to 0.00095) for the mitochondrial DNA COI region. This suggests no segregation of the local populations, supporting the mechanisms IS and PP. (b) T. c. coronatus generated significantly longer spines 70 days after being transplanted to the habitat of a longer-spined population, supporting IS and PP. (c) Individuals caged in the sea for 79 days generated longer spines than individuals in the laboratory, supporting PP. In conclusion, shore-specific morphology of T. c. coronatus arises most likely from phenotypic plasticity and possibly from intragenerational selection.
著者
Matsui Masafumi Nishikawa Kanto Misawa Yasuchika Tanabe Shingo
出版者
Zoological Society of Japan
雑誌
Zoological Science (ISSN:02890003)
巻号頁・発行日
vol.24, no.7, pp.746-751, 2007-07
被引用文献数
3

We conducted an electrophoretic survey to examine systematic relationships of a lotic-breeding salamander Hynobius okiensis endemic to Dogo Island of the Oki Islands, Japan, with several lentic and lotic-breeding Japanese species. Genetically H. okiensis with 2n=56 chromosomes was closer to the lentic-breeding H. nebulosus group (H. nebulosus and H. dunni) with the same chromosome number than to the lotic-breeding H. naevius group (H. naevius and H. kimurae) and H. boulengeriwith 58 chromosomes. Chromosome number reduction from 58 to 56, possibly accompanied with a change in breeding environment from streams to still waters, is estimated to have first occurred in the nebulosus group of Hynobius. A reversal only in breeding habits then seems to have followed in steep, montane environments of the small island of Dogo, resulting in the speciation of H. okiensis.
著者
Endo Hideki Niizawa Nobuharu Komiya Teruyuki Kawada Shinichiro Kimura Junpei Itou Takuya Koie Hiroshi Sakai Takeo
出版者
Zoological Society of Japan
雑誌
Zoological science (ISSN:02890003)
巻号頁・発行日
vol.24, no.10, pp.1005-1011, 2007-10
被引用文献数
2 13

The gross anatomy of the mastication system of the giant anteater (Myrmecophaga tridactyla) was examined by means of three-dimensional image analysis. The anteater rotates the mandibles medially and laterally to control its tongue when it is elongated and to house it when it is relaxed. Three-dimensional CT image analysis demonstrated that the shape and size of the oral cavity changes drastically when the mandibles are rotated. The oral cavity expands bilaterally when the dorsal part of the mandibles bend medially. Macroscopic observations and muscle-weight data supported the observation that the superficial temporal and medial pterygoid muscles act as the main medial and lateral rotators of the mandible, respectively. The low height of the mandibular ramus and the incomplete zygomatic arch in this species represent adaptations for the rotational movement of the mandibles, since they both contribute to the medially oriented transmission of force from the temporal muscles and to preventing collision between the mandibles and the cranium during the rotational movement.